Heating system for dry kilns



' Jan. 12,1943; R.'w. IRWIN EI'AL HEATING SYSTEM FOR DRY mm Filed Dec. 2; 1940 Patented Jan. 12, 1943 Corr NlTE STATES T 2,308,332 iiEA'rntGs'Ys'rEM FOR DRY KiLNs Robert W. Irwinand Cornelius M. Her'z, Grand Rapids, Mich as signors to Irwin Equipment Qompany, Grand Rapids, Mich, a corporation of Michigan 7 Application December 2, 1940, Serial No. 368,136

2 Claims. (01. 34-54) This invention relates to a heating system for I represents the floor'of the dry kiln, 2 the'verdry kilns. The device is particularly intended tical side walls, 3 the top and 4 the end'doors for heatingelongated'chambers used to dry the thereof all constituting a completely enclosed FFICE P finish on furniture or the like wherein it is dechamber. sired to maintain a closely uniform temperature 5 Elongated steam heating radiators 5 are locatand also circulation of air. ed along the Walls of the chamber and are of con- It has been the practice to heat dry kilns with ventional style having headers 6 at each end steam heating radiators having capacity to heat connected by pipes I and steam supply and rethe chamber to a higher degree than desired and turn pipes 8 and 9 are connected with the headers an attempt has been made to maintain a uniform 10 in the customary Way. During operation steam is temperature by intermittently admitting steam constantly supplied to the radiators 5 and they to the radiators and controlling the admission of are constantly hot and dissipate their heat by steam byathermostatlocatedinthe chamberwhich radiation and convection but the capacity of the would automatically stop admission of steam to radiators 5 is slightly insuflicient to raise and the radiator when the temperature reached the maintain the temperature within the chamber to desired degree and to again admit steam to the the desired degree. radiator when the temperature dropped below the An auxiliary heater in is provided which indesired degree. The difliculty with this system cludes a housing II communicating through one has been that the lag in both cooling and heatside of the kiln near the bottom thereof. A radiing the radiator when the steam was either shut 2O ator i2 is located in the housing II but out of ofi from it or admitted to it resulted in a wide heat radiating and convecting relation with the variation of temperature. When the radiator kiln chamber. A circulating fan l3 driven by a had become heated it would continue hot and motor I4 is located in the housing ll adjacent would radiate heat after the steam was shut off the radiator 12 and conduits l5 communicate thus overheating thechamber. Then, when the with the top of the kiln chamber and the interior room temperature dropped below the desired deof the housing ll. When the fan [3 is in operagree it would require a considerable time to heat tion air is circulated from the top part of the the radiator after the steam was admitted to it kiln chamber, where it is warmest, downward so that the room temperature would drop conthrough the housing H and through the auxsiderablybelow normal. iliary radiator l2 and thence into the lower part The object of this invention is to overcome the of the kilnchamber. Operation of the motor [4 difiiculties that have been experienced andto is, controlled by a conventional switch l6 actumaintain a substantially uniform-temperature by ated by a thermostat ll subjected to the kiln utilizing a constantly heated radiator in the kiln chamber temperature. The thermostat and therchamberwhich will have insufficient capacity to mostat actuated switch are of conventional wellheat the chamber to the desired temperature and known construction and form no part of this to combine with it an instantaneously operative invention per se. I auxiliaryheaterwith aforcedair circulator auto- During operation of th kiln the auxiliary ramatically controlled by a thermostat which will diator l2 may be kept constantly hot if desired both raise the temperature to the desired degree or it may be intermittently heated and controlled and maintain it there and also-provide the deby a thermostat. If constantly hot it is in such sired air circulation in thechamber. position relative to the kiln chamber that. its

The invention is hereafter more fully described heat will not be dissipated by either radiation or and'particularly pointed out the claims, refconvection when the fan I3 is not operating. erenceubeing had to the accompanying drawing, When the room thermostat l1 calls for heat the in-which, switch IE will be closed and the motor and fan Fig. 1 is a longitudinal sectional elevation of I4 and I3 will instantly commence operation and,

a dry kiln having the heating system applied will circulate air through the auxiliary radiator th t l2 immediately commencing to increase the room Fig. 2 is a longitudinal sectional plan of the temperature. When the room temperature same on the line 2--2 of Fig. 1, and reaches the desired degree and the thermostat Fig. 3 is a fragmentary transversesectional elell is satisfied the switch It will be opened and vation on the. line 3-3 of Fig. 1. the motor and fan will immediately stop opera- Like numbers refer to like parts in all the figtion ceasing further dissipation of the heat from mes, the auxiliary radiator 1'2 into the kiln chamber.

By this means with a constant supply of heat of nearly sufiicient capacity to raise the temperature to the desired degree and with an auxiliary heat source immediately available the room temperature may be very accurately maintained at the desired degree.

As a modification of this invention it has been found that circulation of air through the radiators 5 will increase their heating capacity or in ther Words, forced circulation of air past the ipes I will increase their dissipation over that hich occurs by mere radiation and convection. Therefore, if the radiators 5 have a capacity somewhat insufi'icient to heat the kiln to the desired temperature when dissipating their heat by convection and radiation only forced circulation of air past them, without the use of auxiliary heating source, will increase their heating capacity and will tend to increase the room temperature. In this phase of the invention the thermostatically controlled motor and fan It and I 3 may be used to control room temperature without the auxiliary radiator I2. Furthermore, taking air from the top part of the kiln chamber where it is hottest and circulating it into the lower part of the kiln chamber also tends to distribute the heat more evenly in the parts of the chamber where the heated air is used and in that part where the thermostat I! is located.

The invention is defined in the appended claims and is to be considered comprehensive of all forms of structure coming within their scope.

We claim: k

1. The combination with a kiln chamber of a constantly operated heating element of insufiicient capacity to maintain the desired temperature by radiation and convection and an auxiliary heating element located out of heat radiating position relative to said kiln chamber and thermostatically controlled intermittently actuated means ior circulating air past said auxiliary heating element into said kiln chamber.

2. The elements defined in claim 1 combined with a conduit for conducting air circulated by said circulating means from the top of the kiln chamber into the lower part thereof.

ROBERT W. IRWIN. CORNELIUS M. HERZ. 

